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1.
The impact of 2 × CO2 driven climate change on radial growth of boreal tree species Pinus banksiana Lamb., Populus tremuloides Michx. and Picea mariana (Mill.) BSP growing in the Duck Mountain Provincial Forest of Manitoba (DMPF), Canada, is simulated using empirical and process-based model approaches. First, empirical relationships between growth and climate are developed. Stepwise multiple-regression models are conducted between tree-ring growth increments (TRGI) and monthly drought, precipitation and temperature series. Predictive skills are tested using a calibration–verification scheme. The established relationships are then transferred to climates driven by 1× and 2 × CO2 scenarios using outputs from the Canadian second-generation coupled global climate model. Second, empirical results are contrasted with process-based projections of net primary productivity allocated to stem development (NPPs). At the finest scale, a leaf-level model of photosynthesis is used to simulate canopy properties per species and their interaction with the variability in radiation, temperature and vapour pressure deficit. Then, a top-down plot-level model of forest productivity is used to simulate landscape-level productivity by capturing the between-stand variability in forest cover. Results show that the predicted TRGI from the empirical models account for up to 56.3% of the variance in the observed TRGI over the period 1912–1999. Under a 2 × CO2 scenario, the predicted impact of climate change is a radial growth decline for all three species under study. However, projections obtained from the process-based model suggest that an increasing growing season length in a changing climate could counteract and potentially overwhelm the negative influence of increased drought stress. The divergence between TRGI and NPPs simulations likely resulted, among others, from assumptions about soil water holding capacity and from calibration of variables affecting gross primary productivity. An attempt was therefore made to bridge the gap between the two modelling approaches by using physiological variables as TRGI predictors. Results obtained in this manner are similar to those obtained using climate variables, and suggest that the positive effect of increasing growing season length would be counteracted by increasing summer temperatures. Notwithstanding uncertainties in these simulations (CO2 fertilization effect, feedback from disturbance regimes, phenology of species, and uncertainties in future CO2 emissions), a decrease in forest productivity with climate change should be considered as a plausible scenario in sustainable forest management planning of the DMPF.  相似文献   

2.
Fossil fuels are currently the major energy source and are rapidly consumed to supply the increasing energy demands of mankind. CO2, a product of fossil fuel combustion, leads to climate change and will have a serious impact on our environment. There is an increasing need to mitigate CO2 emissions using carbon–neutral energy sources. Therefore, research activities are devoted to CO2 capture, storage and utilization. For instance, photocatalytic reduction of CO2 into hydrocarbon fuels is a promising avenue to recycle carbon dioxide. Here we review the present status of the emission and utilization of CO2. Then we review the photocatalytic conversion of CO2 by TiO2, modified TiO2 and non-titanium metal oxides. Finally, the challenges and prospects for further development of CO2 photocatalytic reduction are presented.  相似文献   

3.
Industrialized countries agreed on a reduction of greenhouse gas emissions under the Kyoto Protocol. Many countries elected forest management activities and the resulting net balance of carbon emissions and removals of non-CO2 greenhouse gases by forest management in their climate change mitigation measures. In this paper a generic dynamic forestry model (FORMICA) is presented. It has an empirical basis. Several modules trace C pools relevant for the Kyoto Protocol and beyond: biomass, litter, deadwood and soil, and harvested wood products. The model also accounts for the substitution of fossil fuels by wood products and bioenergy.  相似文献   

4.
Background The use of natural gas has increased in the last years. In the future, its import supply and transport structure will diversify (longer distances, higher share of LNG (liquefied natural gas), new pipelines). Thus the process chain and GHG emissions of the production, processing, transport and distribution might change. Simultaneously, the injection of bio methane into the natural gas grid is becoming more important. Although its combustion is regarded as climate neutral, during the production processes of bio methane GHG emissions are caused. The GHG emissions occurring during the process chain of energy fuels are relevant for the discussion on climate policy and decision making processes. They are becoming even more important, considering the new Fuel Quality Directive of the EU (Dec. 2008), which aims at controlling emissions of the fuel process chains. Aim In the context of the aspects outlined above the aim is to determine the future development of gas supply for Germany and the resulting changes in GHG emissions of the whole process chain of natural gas and bio methane. With the help of two gas consumption scenarios and an LCA of bio methane, the amount of future emissions and emission paths until 2030 can be assessed and used to guide decision processes in energy policy. Results and discussion The process chain of bio methane and its future technical development are outlined and the related emissions calculated. The analysis is based on an accompanying research study on the injection of bio methane to the German gas grid. Two types of biogas plants have been considered whereof the “optimised technology” is assumed to dominate the future market. This is the one which widely exploits the potential of process optimisation of the current “state of the art” plant. The specific GHG emissions of the process chain can thus be nearly halved from currently 27.8?t CO2-eq./TJ to 14.8?t CO2-eq./TJ in 2030. GHG emissions of the natural gas process chain have been analysed in detail in a previous article. Significant modifications and a decrease of specific emissions is possible, depending on the level of investment in the modernisation of the gas infrastructure and the process improvements. These mitigation options might neutralise the emission increase resulting from longer distances and energy intensive processes. In the last section two scenarios (low and high consumption) illustrate the possible development of the German gas supply until 2030, given an overall share of 8–12?% of bio methane. Considering the dynamic emission factors calculated in the former sections, the overall gas emissions and average specific emissions of German gas supply can be given. The current emissions of 215.4 million t CO2-eq. are reduced by 25?% in the low-consumption scenario (162 million t CO2-eq.), where consumption is reduced by 17?%. Assuming a consumption which is increased by 17?% in 2030, emissions are around 7?% higher (230.9 million t CO2-eq.) than today. Conclusions Gaseous fuels will still play a significant role for the German energy supply in the next two decades. The GHG emissions mainly depend on the amount of gas used. Thus, energy efficiency will be a key issue in the climate and energy related policy discussion. A higher share of bio methane and high investments in mitigation and best available technologies can significantly reduce the emissions of the process chain. The combustion of bio methane is climate neutral compared to 56?t CO2/TJ caused by the direct combustion of natural gas (or 111?t CO2/TJ emitted by lignite). The advantage of gaseous energy carriers with the lowest levels of GHG emissions compared to other fossil fuels still remains. This holds true for fossil natural gas alone as well as for the expected future blend with bio-methane.  相似文献   

5.
In the absence of a CO2 tax, the anticipation of a cheaper renewable backstop increases current emissions of CO2. Since the date at which renewables are phased in is brought forward and more generally future emissions of CO2 will decrease, the effect on global warming is unclear. Green welfare falls if the backstop is relatively expensive and full exhaustion of fossil fuels is optimal, but may increase if the backstop is sufficiently cheap relative to the cost of extracting the last drop of fossil fuels plus marginal global warming damages as then it is attractive to leave more fossil fuels unexploited and thus limit CO2 emissions. We establish these results by analyzing depletion of non-renewable fossil fuels followed by a switch to a clean renewable backstop, paying attention to timing of the switch and the amount of fossil fuels remaining unexploited. We also discuss the potential for limit pricing when the non-renewable resource is owned by a monopolist. Finally, we show that if backstops are already used and more backstops become economically viable as the price of fossil fuels rises, a lower cost of the backstop will either postpone fossil fuel exhaustion or leave more fossil fuel in situ, thus boosting green welfare. However, if a market economy does not internalize global warming externalities and renewables have not kicked in yet, full exhaustion of fossil fuel will occur in finite time and a backstop subsidy always curbs green welfare.  相似文献   

6.
In the absence of a CO2 tax, the anticipation of a cheaper renewable backstop increases current emissions of CO2. Since the date at which renewables are phased in is brought forward and more generally future emissions of CO2 will decrease, the effect on global warming is unclear. Green welfare falls if the backstop is relatively expensive and full exhaustion of fossil fuels is optimal, but may increase if the backstop is sufficiently cheap relative to the cost of extracting the last drop of fossil fuels plus marginal global warming damages as then it is attractive to leave more fossil fuels unexploited and thus limit CO2 emissions. We establish these results by analyzing depletion of non-renewable fossil fuels followed by a switch to a clean renewable backstop, paying attention to timing of the switch and the amount of fossil fuels remaining unexploited. We also discuss the potential for limit pricing when the non-renewable resource is owned by a monopolist. Finally, we show that if backstops are already used and more backstops become economically viable as the price of fossil fuels rises, a lower cost of the backstop will either postpone fossil fuel exhaustion or leave more fossil fuel in situ, thus boosting green welfare. However, if a market economy does not internalize global warming externalities and renewables have not kicked in yet, full exhaustion of fossil fuel will occur in finite time and a backstop subsidy always curbs green welfare.  相似文献   

7.
Understanding the effects of climate change on boreal forests which hold about 7% of the global terrestrial biomass carbon is a major issue. An important mechanism in boreal tree species is acclimatization to seasonal variations in temperature (cold hardiness) to withstand low temperatures during winter. Temperature drops below the hardiness level may cause frost damage. Increased climate variability under global and regional warming might lead to more severe frost damage events, with consequences for tree individuals, populations and ecosystems. We assessed the potential future impacts of changing frost regimes on Norway spruce (Picea abies L. Karst.) in Sweden. A cold hardiness and frost damage model were incorporated within a dynamic ecosystem model, LPJ-GUESS. The frost tolerance of Norway spruce was calculated based on daily mean temperature fluctuations, corresponding to time and temperature dependent chemical reactions and cellular adjustments. The severity of frost damage was calculated as a growth-reducing factor when the minimum temperature was below the frost tolerance. The hardiness model was linked to the ecosystem model by reducing needle biomass and thereby growth according to the calculated severity of frost damage. A sensitivity analysis of the hardiness model revealed that the severity of frost events was significantly altered by variations in the hardening rate and dehardening rate during current climate conditions. The modelled occurrence and intensity of frost events was related to observed crown defoliation, indicating that 6-12% of the needle loss could be attributed to frost damage. When driving the combined ecosystem-hardiness model with future climate from a regional climate model (RCM), the results suggest a decreasing number and strength of extreme frost events particularly in northern Sweden and strongly increasing productivity for Norway spruce by the end of the 21st century as a result of longer growing seasons and increasing atmospheric CO2 concentrations. However, according to the model, frost damage might decrease the potential productivity by as much as 25% early in the century.  相似文献   

8.
Motorized traffic is among the biggest CO2-emitting sources and is additionally dominating NOx emission. Engine technology shifts are approaching, while automobiles developed in Germany and Europe are exported worldwide together with the European emission thresholds for cars. The Diesel car boom induced by EU commission, national EU governments and car industry is accordingly analyzed for sustainability and its effects on environment. German CO2 emission reduction numbers by motorized traffic, as claimed by the government, are questioned. Radiative forcing by soot (black carbon) Diesel car emissions is added on the CO2 emissions by fuel combustion. Diesel cars without particle filters are found to cause an atmospheric warming. Modelled and measured NOx emission data are assessed to mismatch considerably. In spite of an ambitious national NOx reduction plan there is excess NOx emission by the German and European Diesel car boom. In this context environmental sustainability of battery electric vehicles (BEV) is investigated. Direct (by car) und indirect (by power plant) emissions (CO2, NOx, PM10, SO2) of cars with internal combustion engines (ICE) and BEVs, respectively, are calculated and compared. CO2-ecoanalysis revealed advantages for BEVs even operated with current German electricity mix based on around 15?% renewable sources.  相似文献   

9.
This study examines the dynamic causality relationship between international tourism and carbon dioxide (CO2) emissions from transport, real gross domestic product and energy use. The vector error correction model and Granger causality test approach have been used to investigate these relationships for the top ten international tourism destinations spanning the period 1995–2013. Results reveal a unidirectional causality running from CO2 emissions to economic growth without feedback; a bidirectional causality between economic growth and energy use; a bidirectional causality between international tourism and economic growth; and a bidirectional causality between international tourism and energy use. They also suggest that energy use and international tourism both contribute to the decrease of emissions level coming from transport sector, while economic growth leads to the increase of CO2 emissions. This study can be used in policy recommendations by encouraging countries to use clean energy and to stimulate tourism sector for combating global warming.  相似文献   

10.
二氧化碳捕集与封存技术(CO_2 capture and storage, CCS)是当前国际上公认的CO_2减排的有效措施,但封存在地下的CO_2仍然因为各种不稳定因素存在泄漏风险,对土壤环境及土壤生态系统产生威胁。选择赤子爱胜蚓为研究对象,通过模拟高浓度CO_2对蚯蚓形态与生理变化的影响,探究CCS泄漏所产生的土壤高浓度CO_2对蚯蚓的毒性效应。研究表明,土壤高浓度CO_2使蚯蚓出现生殖环带肿大、尾部串珠以及断尾等外部形态变化,皮肤和刚毛受到损伤并且表皮发生褶皱等现象;随着CO_2浓度的增加以及暴露时间的延长,蚯蚓的死亡率不断增加,土壤高浓度CO_2对蚯蚓的7 d和14 d半致死浓度分别为26.39%和17.78%;蚯蚓体腔细胞溶酶体中性红保留时间(NRRT)减少。因此,蚯蚓有望作为监测CO_2泄漏的指示生物,NRRT可作为识别CO_2泄漏的敏感指标。  相似文献   

11.
Experiments were performed to measure the emission factors (EFs) of gaseous carbonaceous species, such as CO2, CO, CH4, and non-methane volatile organic compounds (NMVOCs), from the combustion of five types of coal of varying organic maturity and two types of biomass briquettes under residential burning conditions. Samples were collected in stainless steel canisters and 2,4-dinitrophenylhydrazine (DNPH) cartridges and were analyzed by GC-FID/MS and HPLC, respectively. The EFs from crop residue briquette burning were generally higher than those from coals, with the exception of CO2. The dominant NMVOC species identified in coal smoke were carbonyls (41.7%), followed by C2 unsaturated hydrocarbons (29.1%) and aromatics (12.1%), while C2 unsaturated hydrocarbons were the dominant species (68.9%) emitted from the combustion of crop residue briquettes, followed by aromatics (14.4%). A comparison of burning normal crop residues in stoves and the open field indicated that briquettes emitted a larger proportion of ethene and acetylene. Both combustion efficiency and coal organic maturity had a significant impact on NMVOC EFs from burning coal: NMVOC emissions increased with increasing coal organic maturity but decreased as the combustion efficiency improved. Emissions from the combustion of crop residue briquettes from stoves occurred mainly during the smoldering process, with low combustion efficiency. Therefore, an improved stove design to allow higher combustion efficiency would be beneficial for reducing emissions of carbonaceous air pollutants.  相似文献   

12.
Agricultural soils are an important source of greenhouse gases (GHG). Biochar application to such soils has the potential of mitigating global anthropogenic GHG emissions. Under irrigation, the topsoils in arid regions experience repeated drying and wetting during the crop growing season. Biochar incorporation into these soils would change the soil microbial environment and hence affect GHG emissions. Little information, however, is available regarding the effect of biochar addition on carbon dioxide (CO2) and nitrous oxide (N2O) emissions from agricultural soils undergoing repeated drying and wetting. Here, we report the results of a 49-day aerobic incubation experiment, incorporating biochar into an anthropogenic alluvial soil in an arid region of Xinjiang Province, China, and measuring CO2 and N2O emissions. Under both drying–wetting and constantly moist conditions, biochar amendment significantly increased cumulative CO2 emission. At the same time, there was a significant reduction (up to ~20 %) in cumulative N2O emission, indicating that the addition of biochar to irrigated agricultural soils may effectively slow down global warming in arid regions of China.  相似文献   

13.
The most important question raised from issues of environmental degradation is how economic activities bring about changes that will result in pollution. In the pursuit of tourism economy, contrary to popular interest, the travel and tourism (T&T) industry may cause environmental damages through the emissions of carbon dioxide (CO2) from energy consumption in areas such as transportation and delivery of amenities. Given this major concern, this paper attempts to investigate the linkage between tourism and CO2 emissions in Malaysia between 1981 and 2011. In particular, this study fills the knowledge gap by taking a closer look at the impact of international tourist arrivals on CO2 emissions by sector – electricity and heat generation and transport. Results from the bound test method suggest that there exists a long-run relationship among the variables under consideration when CO2 emissions become the dependent variable. The original result is similarly robust to alternatives, which are CO2 emissions from sectors of electricity and heat generation and transport. Furthermore, the vector error correction model causality analysis indicates a causal relationship between tourism and CO2 emissions by transport and electricity and heat generation. Subsequently, several tourism-related policies are drawn from these findings.  相似文献   

14.
The fluorinated compounds sulphur hexafluoride (SF6), perfluorocarbons (CF4, C2F6) and hydrofluorocarbons (HFCs) are atmospheric trace gases with extremely high global warming potentials (GWP). The study examines the real emissions of these compounds in Germany between 1990 and 1995, and develops projections for the years up to 2020. These projections indicate that annual perfluorocarbon releases will drop between the years 1990 and 2000 from 335 t/34 t to 100 t/10 t due to automation measures at the main source (aluminium smelting). Sulphur hexafluoride emissions, however, will remain in the range between 200 and 300 t per annum until the year 2020. By far the largest emitters are car tyres and sound-insulation glazing, non-electrical swithgear, the latter being relatively well sealed and linked to management and reprocessing concepts for used gas. As concerns hydrofluorocarbons which have only been used since 1990 with the specific intention of substituting chlorofluorocarbons (CFCs), an increasing degree of CFC substitution in stationary and mobile refrigeration technology, in canned PUR foams and in asthma sprays must be expected to lead to steeply rising emissions to levels exceeding 9,700 t/a from the year 2007 onwards, if halogen-free alternatives are not used more strongly. Assuming these trends, the cumulative emissions of the stated fluorinated compounds will correspond to a global warming impact of 25 million t CO2 (GWP time horizon: 100 years) by the year 2020.  相似文献   

15.
The Brazilian government has already acknowledged the importance of investing in the development and application of technologies to reduce or prevent CO2 emissions resulting from human activities in the Legal Brazilian Amazon (BA). The BA corresponds to a total area of 5 × 106 km2 from which 4 × 106 km2 was originally covered by the rain forest. One way to interfere with the net balance of greenhouse gases (GHG) emissions is to increase the forest area to sequester CO2 from the atmosphere. The single most important cause of depletion of the rain forest is cattle ranching. In this work, we present an effective policy to reduce the net balance of CO2 emissions using optimal control theory to obtain a compromising partition of investments in reforestation and promotion of clear technology to achieve a CO2 emission target for 2020. The simulation indicates that a CO2 emission target for 2020 of 376 million tonnes requires an estimated forest area by 2020 of 3,708,000 km2, demanding a reforestation of 454,037 km2. Even though the regional economic growth can foster the necessary political environment for the commitment with optimal emission targets, the reduction of 38.9% of carbon emissions until 2020 proposed by Brazilian government seems too ambitious.  相似文献   

16.
This paper examines long-run and short-run dynamics of renewable energy consumption on carbon dioxide (CO2) emissions and economic growth in the European Union. This study employs cointegration tests, Granger causality tests and vector error correction estimates to examine the direction of Granger causality, the long-run dynamics of economic growth and energy variables on carbon emissions. This study analyses time series data from the World Development Indicators over the period from1961 to 2012. The results of this study support a link between renewable energy consumption, economic growth, industrialization, exports and CO2 emissions in the long-run and short-run. The results support that the sign of the long-run dynamics from the endogenous variables to the CO2 emissions variable is negative and significant, which implies that the energy and environmental policies of the European Union aimed at curbing CO2 emissions must have been effective in the long-term. Furthermore, renewable energy consumption and exports have significant negative impact on CO2 emissions in the short-run. However, industrialization and economic growth have positive impact on CO2 emissions in the short-run. The results suggest that both economic growth and industrialization must have been achieved at the cost of harming the environment. The finding suggests that the increasing consumption of renewable energy tends to play an important role in curbing carbon emissions in the region.  相似文献   

17.
In recent years, the world has witnessed an ever-growing concern towards global warming caused by greenhouse gases, such as carbon dioxide (CO2). In order to reduce the emissions of CO2 without limiting economic growth, substantial investments should target the development of clean technology and the expansion of forested areas. Considering the limited availability of resources, investments must be used in the most effective way. The present work proposes a method to efficiently manage these resources by applying the optimal control theory to a new mathematical model that describes the dynamics of the atmospheric CO2. The contributions of this work are twofold: (1) present a model that describes the dynamic relation of CO2 emission with investment in reforestation and clean technology and (2) present a method to efficiently manage the available resources by casting an optimal control problem. The mathematical model uses ordinary differential equations to relate the production of CO2 with forest area and Gross Domestic Product (GDP). The model parameters are adjusted to fit the actual published data. Given an appropriate performance index, the optimal solution is found by numerically solving the Two-Point Boundary Value Problem (TPBVP) that arises from the application of Pontriagyn's Maximum Principle. The sensitivity of the obtained numerical solution is evaluated with respect to the uncertainties in the model parameters. The main objective of this work is to provide a quantitative tool for the efficient allocation of resources to reduce the greenhouse effect caused CO2 emissions.  相似文献   

18.
Boreal forests play an important role in the global balance of energy and CO2. Our previous study of elaborate eddy covariance observations in a Siberian boreal larch forest, conducted both above the forest canopy and at the forest floor, revealed a significant contribution of latent heat flux (LE) from the cowberry understory to the whole ecosystem LE. Thus, in the present study, we examined what factors control the partitioning of whole ecosystem LE and CO2 flux into the understory and overstory vegetation, using detailed leaf-level physiology (for both understory and overstory vegetation) and soil respiration property measurements as well as a multilayer soil-vegetation-atmosphere transfer (SVAT) model. The modeling results showed that the larch overstory's leaf area index (LAI) and vertical profile of leaf photosynthetic capacity were major factors determining the flux partitioning in this boreal forest ecosystem. This is unlike other forest ecosystems that tend to have dense LAI. We concluded that control of the larch overstory's LAI had a relationship with both the coexistence of the larch with the cowberry understory and with the water resources available to the total forest ecosystem.  相似文献   

19.
Flue gas recirculation (FGR) is a low nitrogen oxide (NOX) combustion technology. The present study used standard gas to simulate the cycle gas (the main ingredients of which are oxygen (O2), nitrogen (N2), and carbon dioxide (CO2)). The coal grate-fired process was divided into three zones, namely (1) volatilization zone, (2) main combustion zone, and (3) char combustion and burn-out zone. The effects of FGR on coal combustion and NO emissions were investigated in these zones of a unit-boiler experimental system. An industrial test was then conducted on a chain boiler that previously used FGR. Data showed that if the cycle gas was directed into the furnace from the volatilization zone, the curve of the coal surface temperature moved backwards, the temperature peak increased, and coal ignition was delayed. When the FGR rate was 20%, NO emissions/g coal was 41.8% less than in the absence of FGR, in the overall combustion process except for the volatilization zone. An industrial test demonstrated that FGR decreased the NO emissions and incomplete-combustion loss of gas. NO and carbon monoxide (CO) emissions were reduced by 26.9 and 38%, respectively. These observations may prove to be beneficial in reducing ambient air pollution and saving energy.  相似文献   

20.
Meeting environmental, economic, and societal targets in energy policy is complex and requires a multicriteria assessment framework capable of exploring trade-offs among alternative energy options. In this study, we integrated economic analysis and biophysical accounting methods to investigate the performance of electricity production in Finland at plant and national level. Economic and environmental costs of electricity generation technologies were assessed by evaluating economic features (direct monetary production cost), direct and indirect use of fossil fuels (GER cost), environmental impact (CO2 emissions), and global environmental support (emergy cost). Three scenarios for Finland's energy future in 2025 and 2050 were also drawn and compared with the reference year 2008. Accounting for an emission permit of 25 €/t CO2, the production costs calculated for CHP, gas, coal, and peat power plants resulted in 42, 67, 68, and 74 €/MWh, respectively. For wind and nuclear power a production cost of 63 and 35 €/MWh were calculated. The sensitivity analysis confirmed wind power's competitiveness when the price of emission permits overcomes 20 €/t CO2. Hydro, wind, and nuclear power were characterized by a minor dependence on fossil fuels, showing a GER cost of 0.04, 0.13, and 0.26 J/Je, and a value of direct and indirect CO2 emissions of 0.01, 0.04, and 0.07 t CO2/MWh. Instead, peat, coal, gas, and CHP plants showed a GER cost of 4.18, 4.00, 2.78, and 2.33 J/Je. At national level, a major economic and environmental load was given by CHP and nuclear power while hydro power showed a minor load in spite of its large production. The scenario analysis raised technological and environmental concerns due to the massive increase of nuclear power and wood biomass exploitation. In conclusion, we addressed the need to further develop an energy policy for Finland's energy future based on a diversified energy mix oriented to the sustainable exploitation of local, renewable, and environmentally friendly energy sources.  相似文献   

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